Antistatic agents for hydrophobic fiber



, phobic textile fibers,

United 2,839,431 ANTISTATIC AGENTS FOR HYDROPHOBIC FIBER No Drawing.Application August 26, 1955 Serial No. 530,888

8 Claims. (Cl. 117-139.5)

This invention relates to novel compositions of matter which are'usefulas antistatic agents for hydrophobic textile fiber. More particularly,this invention deals with novel olefine-type interpolymers of diverseesters of acrylic or methacrylic acid, as more fully defined below.

It is an object of this invention to produce novel organic compoundswhich are useful as treating agents for textile fiber. A special objectof this invention is to provide antistatic agents of improved qualitiesfor hydrosuch as nylon, polyethylene terephthalate fibers,polyacrylonitrile fibers, hydrophobic cellulose derivatives and theirvarious modifications.

Fibers of the aforementioned types are well known for their poorelectrical conductivity. As a result, they tend to accumulateelectrostatic charges in working, as for instance in the textile mill,or in service, as for instance in a rug. Such charges may be annoying,for instance, by causing a nylon dress to cling to the body of thewearer, interfering with the intended graceful hang of the garment; butthey are Worse than annoying in the textile mill, where such staticcharges, formed through repeated friction of the fiber, filament oryarn, may prevent proper spinning, drawing, twisting, weaving orknitting.

It has already been proposed in the art to overcome the above noxioustendency by treating the fiber with various antistatic agents, whoseaction apparently depends on the ability of the agent to conductelectricity by a process of ionization. The clifiiculties encountered inthe selection of a proper antistatic agent have been aptly enumerated inU. S. Patent No. 2,676,122, wherein the solution offered to the problemconsisted of selecting certain alkanolamine salts of long-chain alkylphosphates as therein specified.

However, as the commercial use of antistatic agents is being developed,certain new requirements are continu ously added to the problem. Onesuch requirement is durability to washing and cleaning. In other words,it is required that the antistatic effect shall be fast to washing (withwater), laundering (in water, with soap) and dry cleaning (with organicsolvents).

I have now found that antistatic agents of excellent initial, strengthand of satisfactory durability to Washing and dry cleaning are obtainedby polymerizing the novel monoalkoxy polyethylene glycol acrylates ofFormula I hereinbelow in the presence of a minor quantity of glycidylmethacrylate. The copolymer thus obtained is of the olefinic type, andthe components thereof consist of (I) a monoalkoxy polyethylene glycolacrylate of the formula CHz=$- (f(OCH2OH2)n-0R R wherein R designates Hor CH R radical (i. e. an alkyl radical of 1 to 6 Gatoms), While thesubscript n has a value not less than 4 and not greater than 20, and(II) glycidyl methacrylate, which may be represented by the formula t 1on o-o-o-on CHOH l 1 is a lower alkyl tes Patent 0 above 50 to 602,839,431 Patented June 17, 1958 i may be prepared by reacting amonoalkyl ether of a polyethylene glycol as above defined with the acidchloride of acrylic or methacrylic acid.

The initial monoalkyl ethers themselves are generally obtained by aprocess of polymerization; that is, by reacting with ethylene oxide gasupon a lower monoalkyl ether of ethylene or diethylene glycol. Theresulting reaction product therefore consists of a mixture of monoalkylpolyethylene glycols or the above formula with various integral valuesof n. The value of n: in the initial material and in the resultingacrylate esters is thus an average number, and may have integral as Wellas fractional values. i

Some of the initial monoalkyl polyethylene glycols occur in commerce.Thus, methylethers of total molecular weights of 550 and 750, anddesignated in commerce as methoxy polyethylene glycol 550 and methoxypolyethylene glycol 750 are available on the market. The average valueof n in these compounds is therefore approximately 12 and 16,respectively. Others can be readily synthesized by the method aboveindicated.

The interpolymerization of components I and II according tothisinvention may be achieved by known general methods, for instance byheating the two components together in a common solvent, for instancewater, alcohol, dioxane, mixtures of these, tetrahydrofurane, benzene,etc., in the presence of a free-radical polymerization catalyst. Assuitable instances of the latter may be mentioned dibenzoyl peroxide,ammonium or potassium persulfate, azo-bis-isobutyronitrile, and cumenehydroperoxide, although other similar compounds may also be used.Conventional amounts of such polymerization catalysts (or,initiators, asthey are sometimes called) are 0.1% to 0.5% based on the joint weight ofcomponents I and II.

The reaction temperature is generally determined by the activity of thecatalyst selected; that is, a temperature is selected at which thecatalyst will generate free radicals. Conversely the catalyst may beselected on the basis of the temperature at which the reaction is to beoperated, so that free radicals will be obtained at that temperature.The reaction is operable at room temperature and can be run as high asto 'C., especially in organic media; In water, however, it is preferablenot to go C., because the polymer is less soluble in water at higherthan at lower temperatures.

The polymerization system should preferably be about neutral, but it canbe slightly acidic or alkaline; i. e., it may have apH of 4.5 to 8. i

Control is exercised to produce a polymer which is soluble enough to bepadded onto the fiber from an aqueous, alcoholic or aqueous-alcoholicsolution or suspension, but which is nevertheless sufiicientlypolymerized to be converted to an insoluble finish upon curing thefiber. Curing implies heating the treated fiber at temperaturesgenerally in the range of to C. The

insolubilization caused by curing is believed to be due to cross-linkingof the polymer.

It is important to avoid gelation in the p rocess of producing theinterpolymer. Control to this effect may be achieved by one or both ofthe following remedies:

(1) Adding initially a modifier such as Z-mercaptoethanol, whichmoderates the chain growth; and

(2) Holding down the reaction temperature to a value not exceeding about100 C.

The quantity of modifier, when employed, is generally of the order of lto 5 mols percent, based on the polyethylene glycol ester employed.

The physical qualities of the resulting copolymer depend not only on theratio of components I and II, but also on the value of n in the former.The polymers resulting when n is relatively low, say 4 to 6, are solublein benzene and other non-polar solvents, and also, to some extent, inwater. But as the value of n increases, the polymer becomes increasinglysoluble in polar media.

Essentially all copolymers of the above nature (regardless of the valueof it) give an excellent initial, and to some extent durable, antistaticrating on the cured fiber; but exceptional durability of this effect torepeated launderings generally begin at n=6 and increases with the valueof n.

The application of the above copolymers to textile fiber is preferablydone by padding from an aqueous bath, followed by squeezing out theexcess moisture, drying, and curing the fiber at a temperature between105 and 150 C. for a period, varying inversely with the temperature,from 20 to 3 minutes.

The padding bath may be an aqueous, aqueous-alcoholic or aqueous-dioxanesolution of the polymer, if the latter is soluble enough, or an aqueoussuspension if the polymer is not sulficiently soluble. The padding-bathwill generally contain from 1 to 5% of the polymer by weight, and theimpregnated goods will generally be squeezed until they retain about 0.5to 2.5% of the active ingredient by weight based on the weight of thefiber. Higher concentrations or higher retentions of the activeingredient are tolerable, however, except for considerations of economy.

The cured finish is fast to washing with water, with or without soap,and to dry cleaning (with solvents) in the absence of detergents.

When the treated fiber is polyacrylonitrile, improved abrasionresistance is incidentally imparted to the fiber, and the effect isreasonably fast to washing.

It is remarkable that all the aforenoted effects are obtained withlittle if any stiffening of the fiber.

For the purpose of measuring the electrostatic qualities of fabricstreated with my novel agents, the following procedure for testing andthe table of ratings hereinbelow have been adopted as standards.

Testing procedure.-A strip of fabric 3 cm. wide is cut from the sampleto be tested and its electrical resistance at a controlled relativehumidity of 25% is measured on a special apparatus which comprises twoelectrodes separated by a space of 1.25 cm. and having a potentialdifference of 90 volts. The fabric is held in place betweentheelectrodes so as to provide a conducting area 1.25 cm. long and 3 cm.wide. The direct measurement gives the resistance of the mentioned areain ohms. Multiplication of this measurement by.2.4 gives the so-calledresistivity per sq. cm. of the tested fabric. This resistivity is thentranslated into an antistatic rating according to the following table:

Resistivity per sq. cm. Antistatic Rating to 1,000)X10 ohms Excellent.(1,000 to 10,000) X10 ohms. Very good. (10,000 to 50,000) 10 ohms 0o(50,000 to 125,000) X10 Ohms Fair. (125,000 to 500,000) l0 .ohms Poor.Above 500,000 ohms Nil.

Without limiting my invention the following examples 4 i are given toillustrate my preferred mode of operation. Parts mentioned are byweight.

PART A.PREPARATION OF THE MONOALKOXY POLYETHYLENE GLYCOL ACRYLATESExample 1 and the mass was filtered to remove the pyridinehydrochloride. Distillation was then continued and finished under vacuumuntil all the ether was removed. The weight of the residual ester was148 g It was a colorless, oily liquid, soluble in water, alcohol anddioxane.

Example 2 "was then removed until the pot temperature reached 130 C., atwhich point the eerie nitrate test for alcohol on the distillateindicated no more than a trace of methyl alcohol in the system. Thecharge was then cooled to C., and residual methyl acrylate was removedunder vacuum. 83.5 gms. of methoxy polyethylene glycol acrylate wereobtained. The product had the same physical appearance and chemicalproperties as in Example 1.

Example 3 825 g. of methoxy polyethylene glycol 550, 825 g.

of methyl methacrylate, 9.27 g. of nitrobenzene and 0.927 g. of2,6-di(t-butyl)-p-cresol were heated with agitation under nitrogen tothe boil, and methyl methacrylate and water were removd by distillation,until the head temperature reached 99.5 C. After cooling, 7.4 g.. oftetraisopropyl titanate were added, and upon resuming heating the methylalcoholmethyl methacrylate azeotrope which formed was removed. Anotherportion of tetraisopropyl titanate (1.8 g.) was added, and distillationwas continued until the head temperature reached 99 C. At this point thedistillation gave only a faint eerie nitrate test for alcohol andreaction was considered complete.

The charge was then cooled to C., under nitrogen, and 37 ml. ofdistilled water were added with stirring. The mass was steam distilledto remove methyl methacrylate. After cooling the residual mass to roomtemperature, its weight was brought up to 1840 g. by adding distilledwater. The content of methoxy polyethylene glycol methacrylate in themass was found by bromine titration to be 48.5% by weight.

Example 4 Over the next 2 /2 hours 80 g. of benzene-methyl-alcoholazeotrope were collected. 1.0 g. of tetraisopropyl tita nate was thenadded and distillation was continued for an additional hour, until aceric nitrate test showed no alcohol in the distillate. The charge,weighing 1186 g., was then cooled to 40 C. under nitrogen. The excessbenzene and methyl methacrylate were removed by distillation underreduced pressure, until the pot temperature reached 87 C. at a pressureof 0.2 mm. The residue, constituting methoxy polyethylene glycolmethacrylate of the formula I? r CHsO(CH2O 20)1o-C-C=CHz exhibited thesame physical and chemical properties as the product of Example 1.

Example 5 Following the general procedure of Example 1, equivalentamounts of n-hexyloxy-decaethylene-glycol and methacrylyl chloride werereacted in ether solution, in the presence of enough pyridine to reactwith the I-ICl formed. The precipitated pyridine hydrochloride wasfiltered off, the ether evaporated and the monomer dispersed in water asa 30% emulsion. This monomer is soluble in water up to about 5%.

The initial n-hexyloxy-decaethylene-glycol was prepared by condensinghexyl alcohol and ethylene oxide in known manner, using a sodiumcatalyst.

PART B.-PREPARATION AND TESTING OF THE INTERPOLYMERS Example 6 15 g. ofthe ester obtained in Example 1 above and 0.8 g. of glycidylmethacrylate were dissolved in 23.7 g. of water and adjusted by means ofalkali to pH 7. The solution was heated to 65 C. under nitrogen and then20 mg. of ammonium persulfate, (NH S O were added. After one hour, thesolution became very viscous and finally gelled.

The gel was dissolved in a mixture of 12 g. of tetrahydrofuran and 60 g.of dioxane, and was diluted with water to produce a 4% concentration byweight of the copolymer.

Dacron polyester fabric was padded with this solution, then dried andcured at 110 C. for 5 minutes, and finally washed in 0.5% aqueous soapsolution at 160 F. for 30 minutes with agitation.

The fabric thus treated was tested for antistatic action directly aftercuring, after one soaping and after three soapings.

It was found to possess a rating of excellent directly after curing;very good, after the first soaping; and still good, after threesoapings.

The rating of untreated Dacron polyester fabric on the same scale isnil.

Example 7 A solution of 83.5 g. of the methoxy polyethylene glycolacrylate obtained in Example 2 and of 12.5 g. of glycidyl methacrylatein 96 g. of water was adjusted to pH 7 and then heated to 60 C. undernitrogen. 150 mg. of ammonium persulfate were added in small incrementsover a period of 2 hours. The viscosity started to increase rapidly; soover the next hour period water was fed into the mass gradually whilecontinuing the heating, until the concentration of the polymer in thereaction was diluted to 10%.

The aqueous reaction mass was then cooled and diluted further to producea 4% aqueous treatment bath. When Dacron polyester fabric was paddedfrom this bath, squeezed to a 50% wet pick-up (2% solids on weight offabric), dried and cured at 140 C. for 5 minutes, it acquired anantistatic quality of rating excellent. The antistatic effect was stillexcellent after one soaping (in 0.5% aqueous soap solution at 160 F. for30 minutes), and very good after 5 soapings.

The treated fabric was also subjected to repeated dry cleanings (inperchlorethylene) and found to be of excellentantistatic rating after 1cleaning and still very good after five such cleanings.

Example 8 4210 g. of a 57% aqueous solution of the methoxy polyethyleneglycol methacrylate obtained in Example 3 were diluted with 7790 g. ofwater and adjusted with sodium hydroxide solution to pH 7.1. Thesolution was placed in an autoclave under an atmosphere of nitrogen; 15g. of Z-mercapto ethanol were added; the mass was heated under agitationto 50 C., and 240g. of glycidyl methacrylate were added. 40 cc. of a 5%aqueous potassium persulfate solution (adjusted to pH 8) were thenadded, and additional portions of the same catalyst solution were addedin small portions over a period of 5 /2 hours until a total of 275 cc.has been entered. A commercial anti-foaming agent was added in smallportions from time to time as tendency to foam was observed. The masswas then kept at 50 C. for an additional five hours, at which pointconsumption of the monomer, as 1 determined by bromine titration, wascomplete. The mass was then again adjusted to pH 7 by the aid of sodiumhydroxide and finally diluted with water to a 20% concentration of thepolymer.

The resulting solution had a viscosity of 2000 cps. and a density of1.03; both at 25 C. When Dacron polyester fiber was padded with anaqueous bath diluted to 4% polymer concentration and alkalized to pH 10,then dried and cured at C. for 3.5 minutes, it acquired an antistaticeffect of rating excellent, which remained very good after 10 washingsin 0.5% soap solution.

Polyacrylonitrile fiber and nylon fiber, when treated in the samemanner, acquired a similar high degree of antistatic protection.

Example 9 A solution of 100 g. of the product of Example 4 and 25 g. ofglycidyl methacrylate in 375 g. of diethylcarbitol was heated to 75 C.under nitrogen. 30 mg. of a,a-azobis-isobutyronitrile were added. After20 min. another 10 mg. of the catalyst were added. After 2 hours 150 mg.of hydroquinone was stirred into the thick mass to stop thepolymerization, and the copolymer was then bottled as a 23%active-ingredient solution.

When Dacron polyester filament fabric was padded from a 5% solution ofthe above polymer dried and cured at C. for 5 min, it acquiredantistatic protection of rating very good, which did not drop materiallyafter 5 launderings with soap.

Example 10 98 g. of methoxy-deca(ethyleneoxy)-methacrylate (preparedfrorn methoxy decaethylene glycol and methacrylyl chloride according tothe general procedure of Example 1 above) were dissolved in 400 g. ofwater. 2 g. of glycidyl methacrylate and 0.5 g. of ammonium persulfatewere added, and the mass was heated at 65 C. for 16.5 hours. Aspolymerization proceeded, the viscosity of the reaction mass increaseduntil it finally set into a gelled mass of 20%-solids concentration. Bythe aid of vigorous stirring, the reaction mass was dispersed in waterto a concentration of 4%. The particle weight of the dispersed polymerwas determined to be between 600,000 and 700,000.

Evaluation of this composition on Dacron polyester fiber showed it to bean effective antistatic agent with durability through 20 launderingcycles. The hand of the treated fabrics was soft and pliable and wasunaifected by continued laundering.

Polymers of essentially the same qualities are obtained if the 98 g. ofthe methacrylate in the above example are replaced by 112 parts of then-hexyloxy-decaethyleneoxy methacrylate obtained in Example 5 above.

I claim as my invention:

1. The interpolymers obtained by polymerizing, at a temperature notexceeding 100 C. and in the presence of a free-radical polymerizationcatalyst, a mixture of glycidyl methacrylate and of an ester of theformula wherein R designates an alkyl radical of 1 to 6 C-atoms, Rstands for a member of the group consisting of hydrogen and methyl,while the subscript n has a value not less than 4 and not greater than20, the polyalkyleneoxy ester constituting the major proportion of themixture by weight.

2. An interpolymer as in claim 1, the glycidyl methacrylate beingpresent in proportion of 2 to 25% by weight based on the weight of theother ester.

3. A process of producing an interpolymer useful for treating textilefiber, which comprises polymerizing a mixture of glycidyl methacrylateand of an ester of the formula wherein R designates an alkyl radical ofl to 6 C-atoms, R stands for a member of the group consisting ofhydrogen and methyl, while the subscript n has a value not less than 4and not greater than 20, the polyalkyleneoxy ester constituting themajor proportion of the mixture by weight, at a temperature notexceeding 100 C. in the presence of 2-mercapto ethanol. 7

4. A process of improving the electrostatic qualities of hydrophobictextile fiber, which comprises impregnating the same with aninterpolymer as defined in claim 1.

5. A process of improving the electrostatic qualities of hydrophobictextile fiber, which comprises padding said fiber with an aqueous bathcontaining an interpolymer as defined in claim 1, removing excessmoisture from the fiber and then subjecting the latter to heating at atemperature between 105 and 150 C. for a period of time varyinginversely with the temperature from 20 to 3 minutes.

6. Hydrophobic textile fiber having incorporated therein from 0.5 to2.5% by weight of an interpolymer as defined in claim 1, said fiberbeing characterized by increased electrical conductivity compared to thesame fiber when it does not contain said interpolymer.

7. The interpolymers obtained by polymerizing, at a temperature notexceeding C. and in the presence of a free-radical polymerizationcatalyst, a mixture of glycidyl methacrylate and of an ester of theformula wherein R designates an alkyl radical of 1 to 6 C-atoms, Rstands for a member of the group consisting of hydrogen and methyl,while the subscript n has a value not less than 4 and not greater than20, the glycidyl methacrylate being present in proportion of 2 to 25% byweight based on the Weight of the other ester, and the free-radicalpolymerization catalyst being selected from the group consisting ofdibenzoyl peroxide, ammonium persulfate, potassium persulfate,azo-bis-isobutyronitrile, and cumene hydroperoxide.

8. A process of improving the electrostatic qualities of hydrophobictextile fiber, which comprises padding said fiber with an aqueous bathcontaining an interpolymer as defined in claim 7, removing excessmoisture from the fiber and then subjecting the latter to heating at atemperature between and C. for a period of time varying inversely withthe temperature from 20 to 3 minutes.

References Cited in the file of this patent UNITED STATES PATENTS2,565,259 Nyquist Aug. 21, 1951 2,580,901 Erickson et a1. Jan. 1, 19522,606,810 Erickson et al Aug. 12, 1952 2,785,092 Hiestand et a1 Mar. 12,1957 2,785,145 Cooke et a1 Mar. 12, 1957

3. A PROCESS OF PRODUCING AN INTERPOLYMER USEFUL FOR TREATING TEXTILEFIBER, WHICH COMPRISES POLYMERIZING A MIXTURE OF GLYCIDYL METHACRYLATEAND OF AN ESTER OF THE FORMULA